Modern mobile communication tends to provide users with multimedia services at high transfer rates more and more. FIG. 1 is a system architecture diagram of the System Architecture Evolution (SAE). In this figure,
a User Equipment (UE) 101 is a terminal device for receiving data. An Evolved Universal Terrestrial Radio Access Network (E-UTRAN) is a radio access network including a macro base station (eNodeB/NodeB) to provide a UE with a wireless network interface. A Mobility Management Entity (MME) 103 is responsible for managing a mobile context, a session context and security information of a UE. A Serving Gateway SGW (SGW) 104 mainly provides user plane functions, and may be located in the same physical entity as the MME 103. A Packet Data Network Gateway (PGW) 105 is responsible for functions such as charging and lawful interception and may be located in the same physical entity as the SGW 104. A Policy and Charging Rules Function (PCRF) entity 106 provides a policy of Quality of Service (QoS) and charging rules. A Serving GPRS Support Node (SGSN) 108 is a network node device to provide routing for data transmission in a Universal Mobile Telecommunications System (UMTS). A Home Subscriber Server (HSS) 109 is a home ownership subsystem of the UE and is responsible for protecting user information such as a current position of the UE, an address of a service node, user security information, and a packet data context of the UE.
3GPP proposes in Release 12 (Rel-12) demands on enhancement of a small cell. As shown in FIG. 2, target scenarios of small cell enhancement includes a scenario where there is macro cell coverage and a scenario where there is no macro cell coverage and enhancement for indoor and outdoor, ideal and non-ideal backhaul.
In a case where there is macro cell coverage, a technology that carrier aggregation between different base stations can be applied is proposed. A macro cell and a small cell may operate at different frequency bands. There are multiple architectures for the technology of applying carrier aggregation between different base stations, e.g., a Radio Access Network based separation architecture and a Core Network (CN) based separation architecture. The CN based separation architecture means that for a bearer established on a pico cell (pico), data are directly sent to the pico by an SGW of the core network and are not forwarded by a user plane via a macro cell (macro).
At present, there is not a solution to how to correctly notify the core network of switch of bearers for this CN based separation architecture yet.
Especially, there are the following specific problems if an existing path switching process is to be used to notify the core network of switch of bearers.